1. Field of the Invention
This invention relates to dishwasher apparatus and in particular to means for removing soil from the dishwashing liquid during the dishwashing operation.
2. Description of the Background Art
In one form of dishwasher disclosed in U.S. Pat. No. 4,150,680 of Philip P. Johnson et al, which patent is owned by the assignee hereof, an improved structure for separating food soil and the like from the dishwashing liquid is disclosed. The structure is arranged to utilize the combined swirling and longitudinal movement of the dishwashing liquid in the suction passage to the circulation pump for effecting circulation of a portion of the liquid through a soil accumulator having a return passage leading back to the suction portion of the dishwasher liquid circulation means. An impeller is provided in the suction passage for swirling the liquid at relatively high speed to effect the desired transfer of a portion thereof to the soil separating means.
In U.S. Pat. No. 4,168,715 of Raymond W. Spiegel et al, which patent is also owned by the assignee hereof, another form of soil separator is disclosed in a dishwasher structure wherein the soil separating structure is associated with the suction passage leading to the circulation pump. This structure is arranged to utilize the combined swirling and longitudinal movement of the dishwashing liquid in the suction passage produced by a rotary impeller generally similar to that of the above discussed Johnson et al patent. By suitably arranging ports communicating between the suction passage and the separator, the circulation of a portion of the liquid through the separator is automatically effected. More specifically, as disclosed in the Spiegel et al patent, the swirling liquid in the suction passage is urged outwardly from the suction passage through a radially outwardly disposed port and back into the suction passage through a radially inwardly disposed port as a result of the pressure differential resulting from the different radial spacings of the port from the axis of the swirling means.
Another form of soil separator is illustrated in U.S. Pat. No. 1,971,588 of E. S. Stoddard et al. As shown therein, the drain pump is arranged to receive heavier soil particles from the tub sump and force them outwardly into the drain conduit which is normally closed by a valve 91. When the valve is opened, the pump drains the dishwashing machine by pumping the liquid from the bottom portion thereof outwardly through the drain so as to carry with the liquid being drained the soil particles previously delivered to the drain conduit. The drain pump is disposed below the sump, whereas the main liquid circulating impeller is disposed at the bottom wall of the tub.